Search

The substituted acetylacetone 3‐[2‐(pyridin‐4‐yl)ethyl]pentane‐2,4‐dione, C12H15NO2, (1), with an ethylene bridge between the acetylacetone moiety and the heteroaromatic ring, represents an attractive linker for mixed‐metal coordination polymers. In the crystal, (1) adopts an antiperiplanar conformation with respect to the C—C bond in the central ethylene group and almost coplanar acetylacetone and pyridyl groups. The ditopic molecule exists as the enol tautomer, with proton disorder in the short intramolecular hydrogen bond. Single‐crystal neutron diffraction at 2.5 K indicated site occupancies of 0.602 (17) and 0.398 (17). The geometry of the acetylacetone moiety is in agreement with such a site preference of the bridging hydrogen: the O atom associated with the preferred H‐atom site subtends the longer [1.305 (2) Å] and the more carbonyl‐like O atom the shorter [1.288 (2) Å] C—O bond. Based on structure‐factor calculations for the alternative H‐atom sites, reflections particularly sensitive for proton distribution were identified and measured in a second neutron data collection at 170 K. At this temperature, 546 independent neutron intensities were used to refine positional and isotropic displacement parameters for a structure model in which parameters for C and O atoms were constrained to those obtained by single‐crystal X‐ray diffraction at the same temperature. The site occupancies for the disordered proton do not significantly differ from those at 2.5 K. Single‐crystal neutron diffraction at 2.5 K and a subset of neutron data collected at 170 K, combined with information from X‐ray diffraction at the same temperature, suggest static disorder for the proton in the short intramolecular hydrogen bond of 3‐[2‐(pyridin‐4‐yl)ethyl]pentane‐2,4‐dione. [ABSTRACT FROM AUTHOR]

A series of light alkali metal organoperoxides [MOOR] (M=Li, Na, K; R= tBu, CMe2Ph) were isolated in mononuclear form, aided by the tetradentate and neutral NNNN-type macrocycle Me4TACD (L; Me4[12]aneN4=1,4,7,10-tetramethyl-1,4,7,10-tetraazacyclododecane) and strong hydrogen bonds from additional ROOH molecules. The Na and K compounds are characterized by short O−H⋅⋅⋅O contacts, in the case of the Na derivative as short as 2.41 Å. [ABSTRACT FROM AUTHOR]

3-(Pyridin-4-yl)acetylacetone (HacacPy) acts as a pyridine-type ligand towards CdII and HgII halides. With CdBr2, the one-dimensional polymer [Cd(μ-Br)2(HacacPy)Cd(μ-Br)2(HacacPy)2]∞ is obtained in which five- and six-coordinated CdII cations alternate in the chain direction. Reaction of HacacPy with HgBr2 results in [Hg(μ-Br)Br(HacacPy)]∞, a polymer in which each HgII centre is tetracoordinated. In both compounds, each metal(II) cation is N-coordinated by at least one HacacPy ligand. Equimolar reaction between these CdII and HgII derivatives, either conducted in ethanol as solvent or via grinding in the solid state, leads to ligand redistribution and the formation of the well-ordered bimetallic polymer catena-poly[[bromidomercury(II)]-μ-bromido-[aquabis[4-hydroxy-3-(pyridin-4-yl)pent-3-en-2-one]cadmium(II)]-di-μ-bromido], [CdHgBr4(C10H11NO2)2(H2O)] n or [{HgBr}(μ-Br){(HacacPy)2Cd(H2O)}(μ-Br)2]∞. HgII and CdII cations alternate in the [100] direction. The HacacPy ligands do not bind to the HgII cations, which are tetracoordinated by three bridging and one terminal bromide ligand. The CdII centres adopt an only slightly distorted octahedral coordination. Three bromide ligands link them in a (2 + 1) pattern to neighbouring HgII atoms; two HacacPy ligands in a cis configuration, acting as N-atom donors, and a terminal aqua ligand complete the coordination sphere. Classical O-H...Br hydrogen bonds stabilize the polymeric chain. O-H...O hydrogen bonds between aqua H atoms and the uncoordinated carbonyl group of an HacacPy ligand in a neighbouring strand in the c direction link the chains into layers in the (010) plane. [ABSTRACT FROM AUTHOR]